'В классе iControl
Option Explicit

Public Function InitializeControl() As Boolean

End Function

'В контроле
Option Explicit

Implements iControl

Private Function iControl_InitializeControl() As Boolean
    On Error GoTo err_proc

'тут имплементация

    Exit Function
err_proc:
    l_Error.ShowError "AddressEditor.iControl_InitializeControl"
End Function

'Пример использования
For Each obControl In obControlCollection
                 
On Error Resume Next
        Set obControlObject = obControl.object
On Error GoTo err_proc

        If Not obControlObject Is Nothing Then
            If TypeOf obControlObject Is iControl Then
                
                Set obUserControl = obControlObject
                obUserControl.InitializeControl
            End If
        End If
        Set obControlObject = Nothing
        Set obUserControl = Nothing
    Next

Option Explicit

Public Function Test() As Boolean
    
End Function

Option Explicit

Implements Class1

Private Function Class1_Test() As Boolean
    Class1_Test = True
End Function

Option Explicit

Private Sub Command1_Click()
    Dim c As Class1
    Dim control As control
    For Each control In Me.Controls
        If TypeOf control.object Is Class1 Then
            MsgBox "Class1"
        End If
    Next
End Sub